As used herein, the term "tissue and other objects" means and includes human or animal organs, blood vessels, bones, tendons, ligaments and connective or covering tissue or skin as examples of tissue, and sutures, needles, staples, implants, surgical devices and foreign bodies such as shrapnel or bullet fragments, as examples of "other objects". Also as used herein, the term "electrosurgery" means and includes electro-cauterization and electro-cutting of tissue.
During surgical operations, it is often necessary for the surgeon to be able to manipulate blood vessels, ligaments or other tissue precisely, particularly when the surgeon is relatively remote from the surgical site, as is the case in performing endoscopic procedures. As used herein, the term "manipulate" includes such functions as grasping, clamping, cutting and suturing. Among the instruments that are used for manipulating as herein defined are graspers, forceps, clamps, dissectors, incisors, scissors, cauterizers, needle holders, etc. Often the manipulating is achieved by means of an instrument having a two-part handle mechanism, a tissue-interacting head comprising two or more tissue-interacting members (e.g., jaws), and a head supporting and operating means coupling the handle mechanism and the tissue-interacting head for causing the tissue-interacting members to be moved into and out of a closed relation with one another by the surgeon's manipulation of the handle mechanism.
In a typical prior art instrument, the head supporting and operating means comprises a first shaft fixed to one part of the handle mechanism, a second operating shaft disposed in coaxial and telescopic relation with the first shaft, and means connecting the second shaft to the other part of the handle mechanism, so that telescoping movement of one shaft relative to the other shaft is produced when the two parts of the handle mechanism are moved toward and away from one another, with the two shafts coacting to cause opening and closing of the tissue-interacting members according to the direction of telescoping movement of one shaft relative to the other. In one typical grasper construction, two jaws are pivotally attached to one end of an outer hollow shaft, and a linkage operated by an inner shaft causes the jaws to be opened or closed in response to telescoping movement of the inner and outer shafts. In another grasper construction, the jaw mechanism comprises a pair of spring-like jaws carried entirely by the inner shaft, with the outer shaft acting as a collar to provide a collet-like action whereby (a) the jaws are forced together when the inner and outer shafts undergo relative telescoping movement in one direction and (b) the jaws are released so as to allow them to open when the telescoping movement is in the reverse direction.
A number of surgical instruments designed to grasp or otherwise manipulate tissue, are commonly provided with some form of locking means for locking the jaws in a gripping position, so that during a surgical procedure, the surgeon may let go of the instrument to attend to some other task in the same surgical procedure without fear of the instrument failing to retain its grip. Various forms of locking means have been used in prior surgical instruments, e.g., interlocking ratchet teeth on confronting handles of a two-part handle mechanism of the type where each handle has a hole for accommodating a finger or thumb of the surgeon. Other types of locking means may require or use a lever or a button element for engaging or disengaging the locking means.
Many surgical instruments utilize a scissors-like handle design having two pivotally connected handle members with finger loops for enabling the surgeon to grip and manipulate the handle members. Other surgical instruments have so-called "pistol-grip" handle mechanisms, which offer certain advantages over scissors-type handle designs.
Prior surgical instruments, particularly those of the grasper or dissector type, frequently employ electrical elements for electrifying selected portions of the distal end of the instrument for electrosurgery purposes. Some prior art instruments are necessarily limited to monopolar electrification where the patient's body is electrically grounded, while others are adapted for bipolar electrification.
Prior surgical instruments of the foregoing type have been characterized by one or more limitations and disadvantages, such as the possibility of the patient being traumatized as a result of the surgeon exerting excessive manual strength on the handles of the instrument, causing tissue to be grasped too tightly. Another disadvantage is that some prior locking mechanisms which require the surgeon to operate a separate control such as a lever or button to engage or disengage the locking mechanism, are so constructed that the location or construction of such lever or button may render the instrument less comfortable or easy to hold and/or maneuver. Still other forms of prior instruments of the type to which the invention relates suffer from the fact that they are not well adapted for electrosurgery or cannot be adapted for both monopolar and bipolar electrosurgery. Other instruments have the disadvantage that they have handle designs which are uncomfortable to hold or which are difficult to hold steady when the handle mechanism is being actuated.
Prior handle mechanism designs also suffer from the fact that they are not suited for multi-purpose instruments.